A battery pack disclosed in Patent Document 1 includes a battery module in which multiple battery cells are electrically connected to each other, a housing that houses the battery module, a partitioning member that covers one side of the battery module to provide multiple exhaust passages, and a lid that covers the partitioning member. In this way, the battery pack has an exhaust passage provided so as to cover the entire one side of one battery module. The exhaust passage is a passage formed for guiding a gas to a predetermined discharge place when an internal pressure of the battery cell rises and the gas inside of the battery cell is ejected. The exhaust passage is shut off from an outside until reaching the predetermined place. One side of the battery module, the partitioning member, and the lid configure an exhaust duct internally having an exhaust passage.
In the battery pack of Patent Document 1, there is one exhaust duct that defines an exhaust passage for one battery module. For that reason, in the case of a battery pack including multiple battery modules, there is a need to provide the exhaust duct for each of the battery modules.
Further, in order to improve a power storage capacity required for the battery pack, there is a need to increase the number of battery modules in order to increase the number of battery cells. In particular, the requirement is remarkable in the battery packs installed in vehicles requiring a traveling electric power such as electric vehicles, hybrid vehicles and the like. As the number of battery modules increases more, a volume occupied by the exhaust passage in the entire battery pack increases more, which may increase a size of the battery pack.